If I build a new home must I use a 20' rebar as a grounding electrode if available ?
The old wording (before 2005 NEC?) said if available.
Whatever year they changed the wording they changed it to state if present it must be used.
Problem before the change is they wanted us to use CEE whenever possible, but the way it was worded we ended up with footings being installed before an electrician was ever on site in many cases. By the time the electrician did arrive the CEE was deemed not available and was seldom being used.
Exceptions are there for existing installations, but new installations must be connected if the CEE is present. Should you run into a place that has non qualifying reinforcement in the footing - you don't have to bond to it. You do have an option of installing your own qualifying rebar or 4 AWG copper - but that is a design choice not a requirement.